Duplex hydraulic-mechanical jar tool

ABSTRACT

This tool embodies in a single structure comprising inner and outer telescopically related tubular elements confining a body of operating liquid, a hydraulically retarded up-blow jar, actuated by placing a lifting strain on the drill string, and a simple mechanically retarded down-blow jar actuated optionally be effecting a controlled downward pressure of the drill string on the jar. The operation of the two jar mechanisms are accomplished respectively by upward movement of the outer element in an upper portion of the range of vertical movement between said elements and by a downward movement of said outer element through a lower portion of said range of vertical movement. A clearly cognizable signal is provided for the driller to indicate to him the arrival of said outer element in the starting position at which the driller may elect which type of jarring blow he desires to produce in the immediately following operation of the duplex jar of the invention.

Sutliff et al.

1451 Dec. 10,1974

DUPLEX HYDRAULIC-MECHANICAL J AR TOOL Inventors: Wayne N. Sutliff; JimL. Downen,

both of 2931 Pierce Rd., Bakersville, Calif. 93308 Filed:

[22] Feb. 7, 1974 [21] Appl. No.: 440,500

[52] U.S. Cl. 175/297, 175/304 [51] Int. Cl E21b 1/10 [58] Field ofSearch 175/293, 296, 297, 299, 175/300, 302, 304, 306; 166/178 [56]References Cited I UNITED STATES PATENTS 1,885,043 10/1932 Beck 175/304X 2,241,477 5/1941 Rasmussen 175/304 X 2,309,872 2/1943 Shaffer et al.175/304 X 2,621,024 12/1952 Koppl et a1. 175 297 2,659,576 11/1953Linney 175/297 3,685,598 8/1972 Nutter ..175/ 304 2( 2,721,056 10/1955Storm 175/297 2,875,983 3/1959 Sutliff.... 175/304 2,963,101 12/1960Koppl 175/304 x Primary ExaminerDavid Brown [57] ABSTRACT This toolembodies in a single structure comprising inner and outer telescopicallyrelated tubular elements confining a body of operating liquid, ahydraulically retarded up-blow jar, actuated by placing a lifting strainon the drill string, and a simple mechanically retarded down-blow jaractuated optionally be effecting a controlled downward pressure of thedrill string on the jar. The operation of the two jar mechanisms areaccomplished respectively by upward movement of the outer element in anupper portion of the range of vertical movement between said elementsand by a downward movement of said outer element through a lower portionof said range of vertical movement. A clearly cognizable signal isprovided for the driller to indicate to him the arrival of said outerelement in the starting position at which the driller may elect whichtype of jarring blow he desires to produce in the immediately followingoperation of the duplex jar of the invention.

7 Claims, 21 Drawing Figures PATENIEQ SEC 1 0 I974 I saw 10rd 1442.6'. A112.

H05 I IGMS.

PATENTEU mac 1 01974 DUPLEX HYDRAULIC-MECHANICAL JAR TOOL SUMMARY OF THEINVENTION It is a primary object of the present invention to pro- 2 ducean improved hydraulic oil well jar of the type covered by US. Pat. No.2,989,132 issued June 20, 1961 to Jim L. Downen of Bakersfield, Calif.The Downen jar has a fixed packer at the lower end of the outer elementand a floating packer between the upper ends of said elements forconfining operating liquid in the hydraulic chamber of the tool. Splinesprovided within said chamber transmit torque between said elements and apiston provided on said inner element makes a close sliding fit with ashort cylinder extending inwardly from the inner surface of the outerelement when in conjunction therewith, a small vertical escape passagebeing provided in said piston through which liquid can escape from thehigh pressure lower section of the hydraulic chamber into the lowpressure upper section of said chamber while a strain is being placed onthe drill string from which the jar is suspended. As said cylinder risesand moves out of conjunction with said piston the remaining liquid inthe lower section of said chamber rushes past said piston into the uppersection of the chamber resulting in the delivery of an upward jarringblow between impacting surfaces provided respectively on said inner andouter elements.

The return downwardly of the drill string, immediately following for thepurpose of resetting the tool to start another jarring operation, may bevery rapidly accomplished in the Downen jar by virtue of the fact thatwhile the piston and cylinder are in conjunction in this returnmovement, a vacuum is formed in the lower high pressure section of thehydraulic chamber which prevents doing any damage to the jar thuspermitting the driller to effect what is known as a spudding operationin which the drill string is rammed downwardly in resetting the jaruntil the jar is completely collapsed thereby delivering a heavy blowtothe fish.

Notwithstanding the merit of the Downen jar and the facility with whicha down blow may thus be delivered to the fish alternately with thedelivery of a snap action blow upwardly to the fish (with the drillstring in tension) the type of blow delivered in the spudding action isnot nearly as effective as the snap action blow deliverable upwardly bythe Downen jar.

It is a further object of the invention to provide a jar of the generaltype shown in the Downen patent which will offer the driller the optionof delivering snap action jarring blows downwardly with the jar as wellas upwardly.

It is yet another object of the invention to provide such a jar in whicha clear signal will be given the driller in each jar resetting operationwhich will indicate the arrival of the outer element at a point in itsvertical reciprocatory movement relative to the inner element where thedriller has the election of initiating a snap action jar operation ineither an upward or a downward direction.

It is a yet further object of the invention to provide such a jar toolin which the lowering of the outer element of the tool is temporarilybut positively retarded at the point where the restricting cylinderwithdraws downwardly from conjunction with the piston on the innerelement, thereby giving notice to the driller that the jar has beenrestored to its intermediate or starting position from which point thedriller may exercise with 1 Yet another object of the invention is toprovide in said unit an internal male spline sub having heavy integralexternal annular heads at both its opposite ends, and an axially splitfemale spline sub assembled broadside on the spline section of the malesub and united at one end by an overriding ring and at the other by itsscrewing into the internally threaded lower end of the outer tubularelement of the jar.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 5 inclusive are verticalhalf sectional views of successive portions of a preferred embodiment ofthe invention which, taken together, illustrate the parts of the latterdisposed in starting position as when beginning an upward or downwardjarring operation.

FIGS. 6 to 10 inclusive are a set of similar views illustrating themoment of impact in an upward jarring op eration.

"FIGS. 11 to 15 inclusive are a set of similar views illustrating themoment of impact in a downward jarrin operation. I 1

FIG. 16 is a side elevational view of the split tubular head of themechanical retarding device of the downjar structure of the invention.

FIG. 17 is a full cross sectional view taken on the line l7l' 7 of FIG.2 and shows the split head shrinking ring crowning said split tubularhead'and the supporting relation of the quadrant-sections of said headwith said ring.

FIG. 18 is a full cross sectional view taken on the line 18-48 of FIG. 2and shows details of the annular valve piston of the invention and itsenvironment.

FIG. 19 is an elevational view partly in section and shown to a reducedscale of a lower portion of the invention embodying in a single unit allthe elements performing the spline, hammer and anvil functions of theinvention, this view showing said elements on the process of beingassembled.

FIG. 20 is an elevational view of FIG. 19 following the completion ofsaid assembly.

FIG. 21 is a cross sectional view taken on the line 2l-2l of FIG. 20 andillustrating the division of the female spline sub of the invention intotwo halves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring specificallyto the drawings, the invention is shown therein as embodied in ahydraulic oil well jar 25 which includes an outer tubular element 26 andan inner tubular element 27 which are telescopically relatedto eachother for relative axial movement in the operation of the jar. As shownin FIGS. 1 to 5 inclusive the tubular element 26 forms a sleeve whichhouses the jar and is internally threaded at its upper end so as toscrew onto an upper jar 'sub 28 which in turn is adapted to scew ontothe lower pin 29 of a tubular drill string 30 on which the jar 25 issuspended.

The outer tubular element 26 has an inner bore 31 which slideablycontains therein an upper packing member 32 which is recessed forholding internal rings 33 and external 0-rings 34. The lower end of bore31 terminates with a shoulder 35 located at the upper end of acounterbore 40. A tripping ring 41 fits within the counterbore 40against the shoulder 35 and is secured in place by screws 42 which arescrewed into suitable tapped holes provided in outer tubular member 26and fit into suitable recesses provided in the periphery of the ring 41.The ring 41 has an inwardly and upwardly beveled bottom cam face 43which is preferably ground at an angle of 20 with horizontal.

The counterbore 40 presents a smooth cylindrical surface in a shortannular area 44 (see FlG. .2) which will be referred to hereinafter asthe cylinder of the jar 25. Immediately above and below the cylinder 44,the counterbore 40 is relieved by vertical channels 45 and 46 for apurpose to be made clear hereinafter. One or more suitable tapped holesare provided in the outer tubular element 26 of the jar for use inadmitting operating liquid thereto, these holes being closed by fillerplugs 47.

The lower end portion 48 of the outer tubular element 26 (hereinafterreferred to as the stabilizer sleeve) is secured to said element byheavy tapered threads 49, the male threads of which are formed on aheavy annular internal head 50 provided to extend inwardly from theupper end of said sleeve. Provided on the head 50 to extend inwardlytherefrom is a packer 55. Provided in sleeve-48 for a purpose to be madeclear hereinafter, are rather ample fluid ports 56 and 7. Stabilizersleeve 48 has a smooth internal bore 58 and a lower end portion thereofis provided with heavy female internal threads 59. The lower end ofstabilizer sleeve 48 has a male taper 60 of about The threads 59constitute one of the means for assembly of the two halves 61 and 62 ofa female spline sub 63. When assembled, the two halves 61 and 62 offemale spline sub 63 are brought together face-to-face to form saidcomplete sub and so as to provide thereon a heavy cylindrical tubularbody 64 which is machined internally to provide three female splines 65and is turned down at its upper end to provide an annular, hammer 70 andmale threads 71 (matching female threads 59) and a female taper 72matching the male taper 60 on stabilizer sleeve 48. The opposite orlower end of the female spline sub body 64 is turned down to provide alower annular hammer 73 which also receives an integral reinforcing ring74 which is secured in place in uniting relation with the female splinesub halves 61 and 62 by cap screws 75, the heads of which arecountersunk in said ring. The assembly of the female spline sub havingbeen thus advanced by the application to the sub halves of integralreinforcing ring 74 as above described, the two halves as a unit arethen screwed into the threads 59 provided in the lower end portion ofstabilizer sleeve 48 so as to rigidly unite the two sub halves 61 and 62are shown in FIG. 20. Further details relating to the mode of assemblingfemale sub 63 will be made clear hereinafter.

The inner tubular element 27 of the tool comprises upper andintermediate thin walled sleeves 76 and 77 and a relatively heavywalledtubular male spline sub 78. The upper sleeve 76 makes a loosesliding fit upwardly within upper sub 28 when the tool 25 is in startingposition as shown in FIGS. 1-5 inclusive and screws, at its lower end,into a threaded socket provided therefor and recessed in the inner faceof the upper end of intermediate sleeve 77. The exterior face of sleeve76 is concentrically spaced from the bore 31- 77 is an annular head 79having external threads 80 on which is screwed the annular base of amechanical tripping device 88 comprising a split tubular head dividedinto four inwardly yieldable quadrants 87, each bearing a quadrantshaped head 88 which normally underlies tripping ring 41 and has amatching face 89 which parallels the cani face 43 of ring 41 as clearlyshown in FIG. 2. Each head 88 has at its upper extremity a guide wall 90for guiding said head inside of the tripping ring 41.

A short distance downwardly from the lower end of tripping device base85, the external annular head 79 of intermediate sleeve 77 is turneddown to form a shoulder 91 and form a cylindrical surface on which anannular sleeve piston 92 may snugly fit. The external annular sleevehead 79 is also recessed to accommodate an O-ring 93 and is threaded toreceive a nut 94 for tightly uniting piston 92 with annular head 79.

Beneath the external annular head 79 provided on the intermediate sleeve77 of inner tubular element 27,

said sleeve is relatively thin walled so that its external surface 95 isspaced from counterbore 31 of outer tubular element 26 (see FIG. 3) soas to slidingly confine the packer 55 mounted upon the internal face ofannular upper internal head 50 on stabilizer sleeve 48.

The annular sleeve piston 92 is also seen in FIG. 2 to make a closesliding fit with counterbore 40-of external tubular element 26 in thisview which illustrates the invention in its starting position. Here, thepiston 92 is disposed just above the cylinder 44 which is to stayout ofconjunction therewith and entirely opposite the upper relief grooves 45formed in counterbore 40 so as to allow a free passage of operatingliquid vertically past piston 92 and past the cylinder 44 so long aspiston 92 remains so positioned. 1

This piston is provided with a vertical hole which confines a gauge rod101 for gauging the amount of free space in said hole left available fora flow of liquid therethrough and hole 100 is overlapped slightly at itsends by shoulder 91 and nut 94 so as to prevent the escape of rod 101from said hole. Variations in the rate of travel of thecylinder 44relative to the piston 92 during the operation of the jar 25 to effectan upward snap action jarring blow can be accomplished by selecting apin 101, in assembling the tool before using the same, so as toaccomplish the desired rate of travel of the piston 92 during thejarring operation. The external surface of the piston 92 is alsoprovided with an annular groove for receiving an O-ring 102 whichassures a tight sealing fit between the periphery of the piston 92 andthe cylinder 94 when these two elements are in conjunction.

The lower end portion of intermediate sleeve 77 is externally threadedat 103 and provided with an external O-ring 104 to permit said sleeve tobe screwed into and make a sealed connection with an externallyenlarge'd upper annular head 105 provided on the upper end of malespline sub 78. This annular head makes a snug sliding fit with thesmooth cylindrical bore 58 formed in stabilizer sleeve 48. These twoelements are thus always in reinforcing relationship throughout theoperation of the jar 25 which greatly adds to the effisplines 108.

The lower externally thickened annular head 106 of male spline 78 hasprovided thereon a threaded tool pin 109 for connecting the lower end ofthe jar to a drill collar 110 through which the jar 25 is connected tothe fish, recovery of which is being sought.

Attention is now called to the fact that the provision of externallythickened annular heads 105 and 106 at the upper and lower ends of themale spline sub 78 provides on one integral element upper and loweranvil faces 115 and 116. This integration of these two faces in the malespline sub greatly strengthens the tool 25 in the vital shock area ofthe tool. The confining of the upper annular head 105 of the male spline78 .within the stabilizer sleeve 48 so that this head is at all times inclose sliding confinement by said sleeve, also powerfully reinforcessaid male spline sub in the area in which the maximum shocks aresustained by the tool.

The features just noted are made possible in the tool 25 by providingthe female spline sub 63 in two halves 61 and 62 by splitting thefemalesub lengthwise. It thus becomes unnecessary to make one end of themale spline sub of small enough diameter to permit the male spline subto penetrate axially the bore of the female the pounding it must sustainby employing the upper and lower ends of the sub as hammer faces 70 and73.

An added dividend derived from the design just described of the unitshown in FIG. 19, in which is concentrated the spline function as wellas separate pairs of hammer and anvil faces for the performance of bothup as well as down snap action jar operations, is the facility possessedby the jar 25 of permitting the replacesuch sub without the necessity ofremoving the jar from the string and in a relatively short shut down forthis service.

OPERATION An annular chamber 117 is provided between the outer tubularelement 26 and the inner tubular element 27 which is closed at its lowerend by the fixed packer 55 and at its upper endby a sliding packer 32.One or more plugs 47 are provided for use in the conventional manner forfilling chamber 117 with operating fluid,

which is generally a light lubricating oil, and for withdrawing the airfrom this chamber at the time the fluid is delivered thereto. When thetool 25 is in its normal starting position with the parts as shown inFIGS. l-5 inclusive, the entire chamber 117 is filled with operatingliquid. As seen in FIG. 2, the cylinder 44 is out of conjunction at thistime with the piston 92. Lifting the drill string 30 from this positionto bring cylinder 44 v into conjunction with the piston 92 divides thehydraument of the female spline sub 63 in the jar by a new lie chamber117 into a high pressure lower section and a low pressure upper section.The upper section always remains a low pressure area because of thefreedom of the sliding packer 32 to shift vertically in response to anychange in the relative pressures below and above said packer so that thepressure in the uppersection of the hydraulic chamber 1 17 is alwayssubstantially equal to the pressure of the ambient well fluid in whichthe tool 25 is operating. The inner tubular element 27 being connectedthrough the drill collar 1 10 to the fish which is stuck in the well,elevation of the cylinder 44, bringing this into conjunction with thepiston 92, is achieved by the driller raising the drill string 30 totension the same.

With the parts of the tool 25 positioned as shown in FIGS. l-Sinclusive, the driller has two options open to him in operating saidtool. The first of these is to lifton the drill string 30 to bring thecylinder 44 into conjunction with the piston 92 which retards escape ofthe operating liquid in the high pressure section of the chamber 117,thus giving an opportunity to build up a relatively high tension strainon the drill string 30 during the travel of the cylinder 44 upwardlypast the piston 92 and resulting in an upward snap action jarringoperation when the hammer 70 strikes the anvil 115 as shown in FIG. 9.

The location of the respective elements of the jar 25 at the moment ofdelivery ofan upward snap action jarring blow by the tool 25 areillustrated in FIGS. 6-10 inclusive. Immediately following the deliveryof this upward blow through the operation above described of the jar 25,the driller lowers the drill string 30 to return the parts of the jar 25to their positions shown in FIGS. l-5 inclusive; This jar has thefacility of providing a clear indication of the arrival of the parts ofthe jar in this position by the fact that as this position is reached,the tripping ring 41 comes to rest on top of the mechanical trippingdevice 86 by the sloping cam face 43 of said ring engaging the matchingsloping faces 89 provided on the four inwardly yielding quadrants 87 ofsaid device. These faces are cut approximately on a 20 angle withhorizontal for the express purpose of requiring about 20,000 pounds ofpressure on the device 86 before the latter will react by the quadrants87 snapping inwardly to allow the ring 41 to pass downwardly aroundthese quadrants into the position in which said ring is shown in FIG.12. The reaction of the rig to the resistance to downward travel of theouter tubular element 28 provides a readily discernable signal to thedriller at the top of the well indicating to him that the parts of thejar 25 are in the starting position shown in FIGS. l-5 inclusive. Thedriller is thus able to exercise without hesitation at this point theoption as to whether he is going to continue lowering the drill string30 beyond the starting position so as to effect a down snap.

of the type of jarring operation in each instance which he hasprogrammed accomplishing with the jar 25.

Should the driller elect a repetition of the upward jarring operation,each of these operations would start therefore with the parts of the jaras shown in FIGS. 1-5 and constitute a repetition of the upward jarringoperation just described. Whenever the driller elects to follow thearrival of the parts of the jar downward in their starting position asshown in FIGS. 1-5 inclusive, to accomplish a downward snap actionjarringoperation, the driller merely continues his application ofdownward pressure to the drill string 30 on the outer tubular element 28of the jar after the ring 41 is set down on the sloping faces 89 of theinwardly yieldable quadrants 87 of the tripping device 86. With theweight of the drill string 30 often being in the neighborhood of 100,000pounds it takes only a short relaxation of the rig, while lowering thedrill string 30, to apply 10 tons of pressure to the tripping device 86.When this pressure is reached however, a snap action downward jarringoperation takes place in which the annular lower hammer face 73 of thefemale spline sub 63 is snapped downwardly from the position in which itis shown in FIG. 4 into violent impact with the annular hammer 116 asshown in FIG. 15.

It is to be noted that inthe starting position of the parts of the jar25 shown in FIGS. 1-5 inclusive and particularly in FIG. 2, the cylinder44 provided on the outer tubular element 26 has already' passeddownwardly beneath the piston 92 so that there is no or very littleresistance incurred in the passage of operating fluid past said pistonand cylinder during the downward snap action jarring operation justdescribed.- At the start of said operation, the piston 92 and cylinder44 are relatively positioned 'as shown in FIG. 2 and at the conclusionof that jarring operation they are still further separated as shown inFIGS. 12 and 13. j

Following the operation of the jar 25 to effect a downward snap actionjarring blow as shown in FIGS. 11-15 inclusive, the driller immediatelyoperates his rig to lift the drill string 30 the short distance requiredto restore the parts of the jar to the position in which these are shownin FIGS. 1-5 inclusive. In this reaction of the parts of the jar tostarting position, the driller is given a clear signal of the arrival ofthe parts of the jar at this position by the rapid increase in thestrain imposedon continuing the lifting of said drill string, bytheannular cylinder 44 coming into conjunction with the piston 92 therebygreatly increasing the force required to continue lifting on the drillstring. This constitutes a signal to the driller that the parts of thejar have reached their starting position shown in FIGS. 1-5 and, in casethe driller wishes to exercise the option thus given him of repeatingthe downward snap action jarring blow just performed, he can readily dothis by reversing his rig and starting to lower the drill string 30.

It is to be noted that when a downward jarring operation is performedwith the jar 25, the ring 41, after being effective in springing theyielding quadrants 87 inwardly so that these no longer resist thedownward movement of the outer tubular element 25, this ring slidesdownwardly past the quadrant shaped heads 88 and at the conclusion ofdelivery of the downward jarring blow being accomplished, the ring 41has slid downwardly to a point where it is just above the annular base85 of the tripping device 86. During the restoration of the parts of thejar 25 to their starting position, the upward movement of the outertubular element 26 causes the ring 41 to slide up over and constrict theinwardly yielding quadrants 87. Upon ring 41 reaching its startingposition shown in FIG. 12, said quadrant heads 88 will spring backoutwardly under the ring 41 in readiness to initiate another downwardsnap action jarring operation.

The claims are:

1. In a duplex hydraulic-mechanical jar tool, the combination of:

inner and outer telescopically related tubular elements;

means for connecting one of said-elements to a drill string; I

means for connecting the other element to an object to be jarred,referred to herein as afish, telescopically overlapping portions of saidelements providing an annular chamber for confining an operating liquid;

an annular packer supported on one element and slidably engaging theother element to close one end of said chamber;

an annular floating packer disposed between and slidably engaging bothof said elements to close the other end of said chamber;

a relatively short piston extending radially outwardly from said innerelement into said chamber;

a relatively short cylinder provided inwardly on said outer element inwhich cylinder said piston slidably fits to effect a dash pot retardingaction on telescopic movement between said elements when said piston andcylinder are in conjunction; I

the'inner surface of said outer element being relieved in areasimmediately above and below the zone of said cylinder, thereby releasingsaid elements from said dash pot retarding action when said piston andcylinder are out of conjunction;

said cylinder, when in conjunction with said piston, dividing saidchamber into a low pressure section, adjacent to and containing saidfloating'pack'er and a high pressure section adjacent said firstmentioned packer;

twopairs of impact shoulders provided on said elements which comerespectively into axial abutting engagement when opposite ends of theentire range of relative telescopic movement between, said elements arereached,

said tool having an optional operation starting position wherein saidcylinder has just passed out of conjunction with said piston and enteredsaid high pressure chamber section; and

annular cam responsive spring resistance means provided on said elementsin said low pressure chamber section and operative temporarily to haltfurther movement of said cylinder into said high pressure chambersection, until a predetermined heavy downward pressure has been appliedthrough said drill string to said spring resistance means to cause thelatter to suddenly release and thus produce a snap action downward jaroperation,

an upward snap action jar operation being optionally automaticallyaccomplished, starting with the tool in said starting position, byimposing and holding an upward strain of a predetermined value on saiddrill string.

2. A combination as recited in claim 1 wherein said piston makes asubstantially liquid tight peripheral fit with said cylinder when saidpiston and cylinder are in conjunction,

said piston being provided with an axial hole allowing for the escape ofoperating liquid past said piston during the tensioning of said drillstring;

a pin occupying said hole loosely to determine the rate of escape ofsaid liquid, and

means for locking said pin in said hole yet readily permittingreplacement of said pin with another differing in diameter to vary therate of escape of said liquid.

3. A combination as recited in claim 1 wherein saidspring resistancemeans comprises:

a split tubular head co-axially spaced outwardly from said inner elementand mounted at its lower end on said element, said head thus providingan annular series of circumferentially spaced radially flexible armsbearing at their upper ends outwardly, downwardly sloping cam faces, and

a ring means having an inwardlympwardly sloping cam face and fixed onsaid outer element to concentrically overly said cam faces of said armsand be closely juxtaposed therewith when said tool is in startingposition.

4. A combination as recited in claim 3 wherein the angles of said camfaces on said head and said cam ring are approximately with horizontal.

5. A combination as recited in claim 1 wherein a lower end portion ofsaid inner element comprises a male spline sub in which are integrallyunited a central male spline section and upper and lower annular headsections the external diameters of which head sections substantiallyexceed that of said male spline section;

said head sections having provided respectively thereon opposed upperand lower anvil impact faces; and wherein a lower end portion of saidouter element comprises a longitudinally split female spline subincluding two longitudinally separate halves which fit together on saidmale spline section to provide matching female splines;

ring means encircling said male spline sub and axially shiftable overthe lower end of said assembled split female spline sub; and tapered pinthread means provided on an upper end portion of said female spline sub,there being matching threaded box means on the adjacent end portion ofsaid outer element into which said tapered pin thread means screws tocomplete the assembly of said split female spline sub on said integralmale spline sub.

6. In a duplex hydraulic-mechanical jar tool, the

combination of:

inner and outer telescopically related tubular elements;

means for connecting one of said elements to a drill string;

means for connecting the other element to an object to be jarred,referred to herein as a fish;

longitudinallyspaced seal means forming a chamber between said elementsfor confining a body of operating liquid;

dash pot valve means temporarily restricting flow of said liquidlengthwise in said chamber under a heavy strain imposed on said drillstring, then subsequently permitting said flow to produce an upward snapaction jarring blow on said fish;

annular cam responsive spring resistance means provided on said elementsand operative to temporarily halt telescopic contraction of saidelements caused by lowering said drill string, following said blow,until sufficient pressure has built up to produce a downward snap actionjarring blow; and

a spline unit at one end of said tool including an integral male splinesub having heavy external annular heads at its opposite ends, said subcomprising a portion of said inner tubular element,

a female spline sub, split lengthwise and assembled broadside on saidmale spline sub and united when so assembled with said outer tubularelement; and

two pairs of movement limiting annular impact faces, one face of eachpair being provided by an end of said female spline sub and the otherface of said pair being provided by an end face of the annular malespline head located in juxtaposed relation with said first face of saidpair.

7. In a deep well jar tool, the combination of:

inner and outer telescopically related tubular elements;

means for connecting one of said elements to a drill string;

means for connecting the other element to an object to be jarred,referred to herein as a fish;

means between said elements operating to restrain free telescopicmovement between said elements in a given direction responsive to astrain imposed by said drill string for a relatively short distance andthen permitting free movement between said elements;

an integral male spline sub having heavy external annular heads at itsopposite ends, said sub comprising a portion of said inner tubularelement;

a female spline sub, split lengthwise and assembled broadside on saidmale spline sub, an upper end portion of said female spline sub beingprovided with male pin threads;

a relatively thick walled stabilizer sleeve, comprising a lower portionof said outer tubular element, and provided, at its lower end, withfemale box threads matching said male pin threads, the latter beingscrewed into said threads of said stabilizer sleeve in assembling saidfemale spline sub on said male spline sub,

the upper external annular head of said male spline sub making a slidingfit within said stabilizer sleeve thereby mutually reinforcing eachother in all operating positions of the tool; and

means providing hammer and anvil impact faces on said spline stubs whichare brought into collision, when said restraint is relaxed, to transmita snap action jarring blow to said fish upon the termination of saidtelescopic relative movement between said tubular elements.

1. In a duplex hydraulic-mechanical jar tool, the combination of: innerand outer telescopically related tubular elements; means for connectingone of said elements to a drill string; means for connecting the otherelement to an object to be jarred, referred to herein as a ''''fish'''',telescopically overlapping portions of said elements providing anannular chamber for confining an operating liquid; an annular packersupported on one element and slidably engaging the other element toclose one end of said chamber; an annular floating packer disposedbetween and slidably engaging both of said elements to close the otherend of said chamber; a relatively short piston extending radiallyoutwardly from said inner element into said chamber; a relatively shortcylinder provided inwardly on said outer element in which cylinder saidpiston slidably fits to effect a dash pot retarding action on telescopicmovement between said elements when said piston and cylinder are inconjunction; the inner surface of said outer element being relieved inareas immediately above and below the zone of said cylinder, therebyreleasing said elements from said dash pot retarding action when saidpiston and cylinder are out of conjunction; said cylinder, when inconjunction with said piston, dividing said chamber into a low pressuresection, adjacent to and containing said floating packer and a highpressure section adjacent said first mentioned packer; two pairs ofimpact shoulders provided on said elements which come respectively intoaxial abutting engagement when opposite ends of the entire range ofrelative telescopic movement between said elements are reached, saidtool having an optional operation starting posItion wherein saidcylinder has just passed out of conjunction with said piston and enteredsaid high pressure chamber section; and annular cam responsive springresistance means provided on said elements in said low pressure chambersection and operative temporarily to halt further movement of saidcylinder into said high pressure chamber section, until a predeterminedheavy downward pressure has been applied through said drill string tosaid spring resistance means to cause the latter to suddenly release andthus produce a snap action downward jar operation, an upward snap actionjar operation being optionally automatically accomplished, starting withthe tool in said starting position, by imposing and holding an upwardstrain of a predetermined value on said drill string.
 2. A combinationas recited in claim 1 wherein said piston makes a substantially liquidtight peripheral fit with said cylinder when said piston and cylinderare in conjunction, said piston being provided with an axial holeallowing for the escape of operating liquid past said piston during thetensioning of said drill string; a pin occupying said hole loosely todetermine the rate of escape of said liquid, and means for locking saidpin in said hole yet readily permitting replacement of said pin withanother differing in diameter to vary the rate of escape of said liquid.3. A combination as recited in claim 1 wherein said spring resistancemeans comprises: a split tubular head co-axially spaced outwardly fromsaid inner element and mounted at its lower end on said element, saidhead thus providing an annular series of circumferentially spacedradially flexible arms bearing at their upper ends outwardly, downwardlysloping cam faces, and a ring means having an inwardly-upwardly slopingcam face and fixed on said outer element to concentrically overly saidcam faces of said arms and be closely juxtaposed therewith when saidtool is in starting position.
 4. A combination as recited in claim 3wherein the angles of said cam faces on said head and said cam ring areapproximately 20* with horizontal.
 5. A combination as recited in claim1 wherein a lower end portion of said inner element comprises a malespline sub in which are integrally united a central male spline sectionand upper and lower annular head sections the external diameters ofwhich head sections substantially exceed that of said male splinesection; said head sections having provided respectively thereon opposedupper and lower anvil impact faces; and wherein a lower end portion ofsaid outer element comprises a longitudinally split female spline subincluding two longitudinally separate halves which fit together on saidmale spline section to provide matching female splines; ring meansencircling said male spline sub and axially shiftable over the lower endof said assembled split female spline sub; and tapered pin thread meansprovided on an upper end portion of said female spline sub, there beingmatching threaded box means on the adjacent end portion of said outerelement into which said tapered pin thread means screws to complete theassembly of said split female spline sub on said integral male splinesub.
 6. In a duplex hydraulic-mechanical jar tool, the combination of:inner and outer telescopically related tubular elements; means forconnecting one of said elements to a drill string; means for connectingthe other element to an object to be jarred, referred to herein as a''''fish;'''' longitudinally spaced seal means forming a chamber betweensaid elements for confining a body of operating liquid; dash pot valvemeans temporarily restricting flow of said liquid lengthwise in saidchamber under a heavy strain imposed on said drill string, thensubsequently permitting said flow to produce an upward snap actionjarring blow on said fish; annular cam responsive spring resistancemeans provided on said elements and operative To temporarily halttelescopic contraction of said elements caused by lowering said drillstring, following said blow, until sufficient pressure has built up toproduce a downward snap action jarring blow; and a spline unit at oneend of said tool including an integral male spline sub having heavyexternal annular heads at its opposite ends, said sub comprising aportion of said inner tubular element, a female spline sub, splitlengthwise and assembled broadside on said male spline sub and unitedwhen so assembled with said outer tubular element; and two pairs ofmovement limiting annular impact faces, one face of each pair beingprovided by an end of said female spline sub and the other face of saidpair being provided by an end face of the annular male spline headlocated in juxtaposed relation with said first face of said pair.
 7. Ina deep well jar tool, the combination of: inner and outer telescopicallyrelated tubular elements; means for connecting one of said elements to adrill string; means for connecting the other element to an object to bejarred, referred to herein as a ''''fish;'''' means between saidelements operating to restrain free telescopic movement between saidelements in a given direction responsive to a strain imposed by saiddrill string for a relatively short distance and then permitting freemovement between said elements; an integral male spline sub having heavyexternal annular heads at its opposite ends, said sub comprising aportion of said inner tubular element; a female spline sub, splitlengthwise and assembled broadside on said male spline sub, an upper endportion of said female spline sub being provided with male pin threads;a relatively thick walled stabilizer sleeve, comprising a lower portionof said outer tubular element, and provided, at its lower end, withfemale box threads matching said male pin threads, the latter beingscrewed into said threads of said stabilizer sleeve in assembling saidfemale spline sub on said male spline sub, the upper external annularhead of said male spline sub making a sliding fit within said stabilizersleeve thereby mutually reinforcing each other in all operatingpositions of the tool; and means providing hammer and anvil impact faceson said spline stubs which are brought into collision, when saidrestraint is relaxed, to transmit a snap action jarring blow to saidfish upon the termination of said telescopic relative movement betweensaid tubular elements.